In an Android project, the res/ (resources) folder contains all the non-code assets like UI layouts, images, themes, colors, and strings. These resources help in creating a scalable, multilingual, and responsive UI.
📂 res/ Directory Overview
app/src/main/res/
│── drawable/
│── mipmap/
│── layout/
│── values/
│── raw/
│── xml/
│── font/
│── animator/
│── anim/
│── menu/
│── color/
Each folder has a specific purpose. Let’s discuss them in detail.
🔹 1. drawable/ (Images & Graphics) 🎨
Contains images, shape drawables, and vector assets used in UI elements.
📌 Types of Drawables:
| File Type | Description | Example File |
|---|---|---|
| Bitmap Images | Stores PNG, JPG, WEBP images | logo.png, background.jpg |
| Vector Drawables | XML-based scalable images | ic_launcher.xml |
| Shape Drawables | XML files for gradients, borders, buttons | rounded_button.xml |
| State Drawables | XML for button states (pressed, focused) | button_selector.xml |
📌 Example: Button Shape Drawable (button_background.xml)
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#FF6200EE"/>
<corners android:radius="8dp"/>
</shape>
🔹 Best Practice: Use Vector Drawables instead of PNGs to save storage.
🔹 2. mipmap/ (App Icons) 🏞️
- Stores app launcher icons in different resolutions.
- Used instead of
drawable/for better scalability and performance. - Common sizes:CopyEdit
mipmap-hdpi/ mipmap-mdpi/ mipmap-xhdpi/ mipmap-xxhdpi/ mipmap-xxxhdpi/
📌 Example: Setting App Icon in AndroidManifest.xml
<application
android:icon="@mipmap/ic_launcher"
android:roundIcon="@mipmap/ic_launcher_round">
</application>
🔹 Best Practice: Use adaptive icons for consistency across devices.
🔹 3. layout/ (UI Layout Files) 📄
- Contains XML files that define the user interface (UI) structure.
- Used for activities, fragments, RecyclerView items, dialogs, etc.
📌 Example File Structure:
res/layout/
│── activity_main.xml
│── fragment_dashboard.xml
│── item_list.xml
📌 Example: Activity Layout (activity_main.xml)
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/textTitle"
android:text="Hello World!"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
🔹 Best Practice: Use ConstraintLayout for flexible and responsive UI design.
🔹 4. values/ (App-wide Constants) 🏗️
Contains XML files storing reusable values like colors, dimensions, styles, and strings.
📌 Common Files in values/ Directory:
| File | Purpose |
|---|---|
strings.xml | Stores text for localization. |
colors.xml | Defines app color palette. |
dimens.xml | Stores dimensions (margins, text sizes). |
styles.xml | Stores themes & styles for UI consistency. |
📌 Example: strings.xml
<resources>
<string name="app_name">MyApp</string>
<string name="welcome_message">Welcome to MyApp!</string>
</resources>
📌 Example: colors.xml
<resources>
<color name="primaryColor">#6200EE</color>
<color name="background">#FFFFFF</color>
</resources>
🔹 Best Practice: Never hardcode text and colors in XML or Java/Kotlin. Use values/ instead.
🔹 5. raw/ (Media & Other Files) 🎵
- Stores raw assets like MP3, MP4, JSON, text files.
- Used for audio, video, configuration files, etc.
📌 Example: Play Audio from raw/ Folder
MediaPlayer mediaPlayer = MediaPlayer.create(this, R.raw.sound_file);
mediaPlayer.start();
🔹 Best Practice: Use res/raw/ for media files instead of assets/.
🔹 6. xml/ (App Configurations) ⚙️
- Contains configuration files like permissions, preferences, and network security settings.
📌 Common Files:
| File | Purpose |
|---|---|
network_security_config.xml | Defines security settings (HTTPS rules). |
preferences.xml | Stores shared preferences (settings). |
📌 Example: network_security_config.xml
<network-security-config>
<domain-config cleartextTrafficPermitted="false">
<domain includeSubdomains="true">example.com</domain>
</domain-config>
</network-security-config>
🔹 Best Practice: Use xml/ for app-wide settings instead of hardcoding.
🔹 7. font/ (Custom Fonts) 🆎
- Stores custom fonts for app text styling.
- Supports TTF and OTF font files.
📌 Example: Adding Custom Font (font/roboto.ttf)
<TextView
android:text="Hello"
android:fontFamily="@font/roboto"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
🔹 Best Practice: Store all fonts in res/font/ for easy access.
🔹 8. anim/ & animator/ (Animations) 🎬
- Stores animation XML files for UI effects.
📌 Example: Fade In Animation (res/anim/fade_in.xml)
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="500"
android:fromAlpha="0.0"
android:toAlpha="1.0"/>
🔹 Best Practice: Use animator/ for property animations and anim/ for view animations.
🔹 9. menu/ (Navigation Menus) 🍔
- Defines toolbar menus, bottom navigation, and contextual menus.
📌 Example: Toolbar Menu (menu_main.xml)
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/action_settings"
android:title="Settings"
android:icon="@drawable/ic_settings"
android:showAsAction="always"/>
</menu>
🔹 Best Practice: Use menu/ for toolbar and bottom navigation menus.
🚀 Summary: Why Use Default Resource Folders?
✅ Better organization of assets.
✅ Easier localization & theme management.
✅ Efficient memory & performance optimization.
✅ Improves code maintainability and scalability.